Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$78.72	4.840%	$82.53	$82.53	$82.55	$82.50
Purchase #2	$73.31	4.863%	$76.8751	$76.88	$76.90	$76.90
Purchase #3	$212.37	13.266%	$240.543	$240.54	$240.55	$240.50
Purchase #4	$248.42	3.245%	$256.4812	$256.48	$256.50	$256.50
Purchase #5	$88.42	13.180%	$100.0738	$100.07	$100.05	$100.10
Purchase #6	$150.76	8.843%	$164.0917	$164.09	$164.10	$164.10
Purchase #7	$240.83	4.690%	$252.1249	$252.12	$252.10	$252.10
7 purchase totals =	$1,092.83		$1,172.7197	$1,172.71	$1,172.75	$1,172.70